In an effort to reduce the weight of vehicles and improve fuel efficiency of vehicles, aluminum body parts are being incorporated into vehicles. The truck bed of a pick-up truck is a large body part that can result in significant weight savings if it is made of aluminum instead of steel. The truck bed may be mounted on a steel frame provided to assure the strength and durability of the vehicle. The combination of aluminum parts and steel parts in an assembly may cause galvanic corrosion.
As shown in prior art FIGS. 1 and 2, a pick-up truck bed 10 may be secured with bolts 12 to the frame 14. The bolts 12 are inserted into truck bed mounting holes 16 defined by the truck bed 10. A crush-tube 20 and crush-tube reinforcement washer 22 receive the bolt 12 between the truck bed 10 and the cross-member 18. A reinforcement hole 24 is defined by the crush-tube reinforcement washer 22. The cross-member 18 may include a seal 26 within a mounting hole 28 formed in the cross-member 18 that receives the bolt 12. A J-nut 29 may be used to retain the attaching nut 30 that secures the bolt 12 to the assembly.
Accelerated galvanic corrosion may occur at the edge of the mounting hole 28 defined by the cross-member 18 and a frame mounting hole 32 defined by the steel frame 14. The inner diameter of the crush-tube 20 is larger than the mounting hole 28 in the cross-member 18. The crush-tube 20 does not maintain sufficient contact around the edge of the mounting hole 28 in the cross-member 18. Abrasion of the anti-corrosion e-coat on the cross-member 18 may lead to corrosion initiating at the mounting hole 24 that may propagate under the crush-tube 20. Abrasion of the components used to mount the truck bed 10 on the frame 14 can cause gage loss and clamp load loss in the bolted connection over time.
This disclosure is directed to solving the above problem and other problems as summarized below.